Self-compensated and electrically heated reducer for compressed gas or L.P.G.

ABSTRACT

A self-compensating and electrically heated reducer for compressed gas or l.p.g. comprising, a supporting body, a chamber formed inside the body; a diaphragm; an opening inlet between an entrance and the chamber; a closing mechanism for the opening inlet controlling the flow rate of fuel owing to the action of manoeuvring elements, kinematically connected to the diaphragm, on the device controlling the pressure of the fuel coming from the bottle; a mechanism which acts on at least one of the manoeuvring elements to cancel the resultant of the action of the pressure of the fuel on the mechanism; electrical resistors connected with the feeding system in the engine placed in thermic contact with the walls of the body near the inlet.

BACKGROUND OF THE INVENTION

The present invention refers to the reducers for combustible gases orl.p.g. used for feeding internal combustion engines and housed inbottles. These combustible gases are employed for feeding internalcombustion engines for motor transport or for stationary equipment.

Since the pressure of the gas housed in the bottle decreasesprogressively with its consumption from a value of several hundreds ofbars to zero, the uncontrolled forces to which the lever in the pressureregulator is subjected vary from some hundreds of Newtons (or N. x m.)to zero. In the first case, the uncontrolled forces are equal to theforces which the lever receives from the controlling diaphragm of theflow rate and the outlet pressure of the gas; in the second case theyare zero. The precise degree of adjustment is negatively affected to amarked degree by the progressively decreasing variation of these forces.

As a result of the lack of precise adjustment and particularly when thepressure of the gaseous fuel is high, irregularities occur in the idlingspeed of the motor, consumption is higher than usual, and there is anuncontrollable emission of pollutants.

The irregularities in the slow running of the engine, the increasedconsumption and emission of polluting gases are aggravated by thedifferences in the amount of heat, which in standard water heatexchangers installed in the traditional pressure reducers is transmittedto the outflowing fuel emitted in a gaseous state by the reducer.

U.S. Pat. No. 1,450,236 refers to a pressure reducer according to thepreamble of independent claim 1 herein; in a supporting body of saidreducer a chamber is housed, the chamber presents an entrance and anoutlet which are respectively connected with a source of a compressedfluid and a device of use.

A compensating mechanism is capable of cancelling the momentum whichresults from the action of the gas pressure on a manoeuvring devicewhich is controlled by a main diaphragm of the reducer.

The manoeuvring device comprises a two-arm lever which pivots on a pivotfulcrum under the action both of a plunger, which acts the first arm anda spring which urges the second arm of the lever. In addition the leveris mechanically connected with the main diaphragm.

EP-A-0 182 952 discloses an electrically heated reducer for compressedgas or l.p.g. having electrical resistors connected with the feedingsystem of the engine placed in contact with the walls of the reducerbody.

Said resistors are housed in a notch of an inner wall of the reducer andmaintained adherent to the lower surface of said wall by means ofsprings placed between the upper surface of resistors and the lowersurface of a metal plate fixed to the upper surface of said wall.

The purpose of this invention is to obviate these disadvantages.

The invention, as claimed, solves the problem by creating a pressurereduction unit which is self-compensating and electrically heated forcompressed gases or l.p.g., by means of which the resulting thrust orthe consequent momentum arising from the thrusts on the regulationlever, due to the pressure of the fuel contained in the bottle, arereduced to zero whatever the pressure, and the fuel which is emitted ina gaseous state from the reducer is heated to the same amount of heatper unit of mass of fuel supplied in every thermic state of the engine.

The advantages of the present invention lie in the possibility ofcontrolling the pressure and maintaining constant the temperature of thefuel which is fed by the pressure reducer for every value of thepressure of the fuel contained in the bottle. This is achieved by meansof the diaphragm and of the specially placed electrical resistors in theregulator. In this way, the regular idling speed of the engine, ameasured consumption of fuel and a limited and controlled emission ofpollutants may be obtained.

BRIEF DESCRIPTION OF THE INVENTION

In a preferred embodiment of the invention the self-compensating andelectrically heated reducer for compressed gas or l.p.g. comprises: asupporting body; a chamber connected to an entrance and an outlet; adiaphragm which at each variation of the internal pressure of thechamber owing to the different amounts of gas fed controls a closingmechanism of an opening inlet to keep the pressure inside the chamberconstant between the entrance, which connects with a bottle forcompressed fuels or l.p.g., and the outlet, which connects with aninternal combustion engine, in response to the vacuum caused by theengine; the opening inlet being situated at the end of a first channelplaced in the body between the entrance and the chamber, and the closingmechanism for the opening inlet controlling the flow rate of fuel, owingto the action of manoeuvring elements kinematically connected to thediaphragm, on the closing mechanism controlling the pressure of the fuelcoming from the bottle; a thrusting mechanism which acts on at least oneof the manoeuvring elements to cancel the resultant or the momentumwhich results from the action of the pressure of the fuel on themanoeuvring elements wherein the diaphragm is connected with a first armof the manoeuvring lever by means of a connection rod which engages witha second arm of the lever, and the closing mechanism is situated at theend of a first plunger which acts on the second arm by means of thethrusting action brought about by the pressure of the fuel in the firstchannel, a second channel, which receives the thrusting mechanism, beingdisposed between the entrance and the chamber; the lever having a thirdarm opposite the first arm with reference to the pivot on which itpivots; the thrusting mechanism urging on the third arm to negate themomentum of the first plunger's thrust with a thrust due to the pressureof the fuel in the second channel.

In a particularly preferred embodiment, electrical resistors connectedwith the feeding system in the engine are placed in thermic contact withthe walls of the body.

Advantageously the electrical resistors are placed near the openinginlet.

Preferably the resistors present a resistivity which varies in inverseproportion to the temperature.

BRIEF DESCRIPTION OF THE FIGURE

Further advantages, details and salient features of the invention willbe outlined in the following description of a preferred embodiment ofthe reducer as in the present invention, with reference to theaccompanying single FIGURE of drawings which is a vertical section viewof a reducer as in the present invention.

DETAILED DESCRIPTION

The reducer illustrated in the FIGURE forms a part of a feeding systemof an internal combustion engine fed by compressed gases or l.p.g.,comprising known structures and components, which are not illustrated.

DETAILED DESCRIPTION OF A PREFERRED EMBODIMENT

The reducer as illustrated consists of a supporting body 1 which has anentrance 2 connected with a bottle (not shown) and containing acompressed gas like methane, acetylene, hydrogen or l.p.g.

The entrance 2 is connected with a first rectilinear channel 3 having afirst diameter Φ₁ and a second channel 4 having a second diameter Φ₂which is greater than the first diameter Φ₁ channels 3 and 4 being cutin the body 1. Channel 3 leads into a chamber 5 by means of an openinginlet 6 controlled by a closing mechanism 7; the closing mechanism 7opens and closes the opening inlet 6 according to the axial movements ofa first plunger 8, which moves within a guiding perforation 9 coaxial tothe first channel 3. The plunger 8 is integral with a push rod 10 whichrests on a first arm 11 of a manoeuvring lever 12 pivoting in a pivot13, the pivot 13 being supported by body 1.

The function of the push rod 10 is to reduce the dimensions of theplunger 8 and to reduce its weight so as to reduce its inertia.

In use, the plunger 8 is free to move in direction F₄ owing to thethrust of the pressure of the fuel which is emitted from the openinginlet 6 when the lever turns in a clockwise direction; the plunger movesin the direction F₃ of the lever 12, which rotates in an anti-clockwisedirection to close the opening inlet 6 by means of the closing mechanism7, the lever 12 maintaining the closing position of plunger 8 in thisposition.

A second arm 14 of the lever 12 presents an end 15 which iskinematically connected to a connecting bushing 16 integral with an end17 of a manoeuvring rod 18. The manoeuvring rod 18 is connected to adiaphragm 19 by means of two rigid plates 20 and 21; a spring 25 presseson plate 20.

In the embodiment illustrated in the FIGURE, the end 15 is introducedinto a spherically jointed housing 22 situated in the bushing 16 totransmit the movements of the latter with lever 12; the coupling betweenthe housing 22 and end 15 is a free coupling permitting the rotation ofend 15 around the centre of the housing 22.

The manoeuvring rod 18 moves with the diaphragm 19 in the two directionsindicated by the arrows F₁ and F₂ which, respectively, permit thediaphragm 19 to increase and reduce the volume of the chamber 5.

A channel 23 connects the chamber 5 to an outlet 24 which, in its turn,is connected to other components of the feeding system (not shown).

On the basis of this explanation and the accompanying illustration, andif we were to consider the second channel to be non-existent, thedisadvantages of traditional reducers may readily be understood.

The actions which operate on lever 12 are due both to the movements ofthe diaphragm 19 and to the thrust resulting from the pressure of thefuel on the closing mechanism 7. The first actions are controlled by thecharacteristics of the membrane 19 and by the pre-loading of theadjustment of the spring 25; the actions are therefore capable of beingcontrolled.

The actions due to the thrust of pressure of the fuel cannot becontrolled, and their intensity varies from several newtons. to zeroaccording as to whether the bottle is full or empty. It is obvious thata thrust of several N. would have an adverse effect on the preciseadjustment by the diaphragm 19 of the flow rate. In fact, when thediaphragm moves in direction F₁, the closure of the opening inlet 6 bythe closing mechanism 7 is prevented by the thrust of pressure of thefuel on the same element 7; when the diaphragm 19 moves in direction F₂,the opening of the opening inlet 6 by the closing mechanism 7 isfacilitated by the same pressure. These actions caused by the pressureof the fuel are uncontrollable and vary from an intensity whichapproximates closely to the intensity of the action of the diaphragm 19.When the bottle is full, and during the opening of the opening inlet 6,these actions are added to the actions of diaphragm 19; when the bottleis empty, the same actions are zero.

To correct these disadvantages, a second plunger 26 is housed in thechannel 4 which moves in a part 27 of the channel 4 in the directions F₃and F₄. Since the part 27 is parallel with the channel 3, the directionsF₃ and F₄ of the movements of the plunger 26 are parallel with thedirection of the movements of the first plunger 8. In addition, an end28 of the plunger 26 is in contact with the end 29 of a pusher 30 fittedwith a sliding housing in a cylindrical cavity 31 coaxial to part 27 ofchannel 4. The movements of the pusher 30 occur in the directions F₃ andF₄ ; a second end 32 of the pusher 30 rests on a third arm 33 of thelever 12, arm 33 being opposite the first arm 11 in relation to pivot13.

The pusher 30 placed between the plunger 26 and the arm 33 serves toarticulate the thrusting means formed by the piston and the pusher 30.

Sealing means to prevent an unchecked flow of fuel towards the chamber 5through the channel 4 and part 27, have been provided. These consist ofan elastic ring 34 and a metallic ring 35, respectively, being housed ina cavity 36, in which the piston 26 moves, and in which part 27 ofchannel 4 terminates.

As may be seen from the FIGURE, it is evident that the lever 12 receivestwo thrusts owing to the pressure of the fuel in channels 3 and 4; thefirst thrust has the effect of rotating the lever 12 in a clockwisedirection; the second thrust rotates lever 12 in an anti-clockwisedirection, so as to cancel the movement due to the first thrust and tomaintain the lever 12 under the control of the diaphragm 19.

Since the second piston 26 encounters friction owing to the presence ofthe blocking devices 34 and 35, an advantage in a preferred embodimentis that the diameter Φ₂ of channels 4 and 27 should be greater than thediameter Φ₁ of channel 3 in order to negate the momentum of the thrustscaused by the pressure of the fuel on lever 12.

As shown in the FIGURE, the walls 38 which enclose the area of body 1next to the opening 6 present a cavity which houses the electricalresistors 37 connected with the electrically operated feeding system ofthe engine. These resistors are placed in thermic contact with the walls38 to heat the fuel which, when flowing out from the opening inlet 6,expands and cools; they are electrically isolated from the body 1 bymeans of isolators (not shown).

The resistors 37 have the advantage of being type P.T.C., theresistivity of which varies according to the temperature to which theyare subjected, the purpose being to give quantities of heat for units oftime which decrease in duration as the temperature rises. In the heatingphases, when the heat which is required to heat the fuel as it emergesin an expanded form from the inlet is greater, the resistivity of theresistors 37 diminishes, and the amount of heat given per unit of timeby the resistors is greater; in the working phases of the engine at astabilized temperature, when the amount of heat required to heat thefuel is generally less, the resistivity of the resistors 37 increases sothat they can give smaller amounts of heat per each unit of time. Since,generally speaking, heat absorbed by the fuel which passes through theopening inlet 6 depends on the flow rate, the resistors maintain thetemperature of the fuel constant, changing their electrical resistivityaccording to the temperature, so as to give greater amounts of heat perunit of time in direct proportion to the flow of the fuel. In this waythe temperature of the fuel at the outlet of the reducer is virtuallyconstant during any working condition and whatever the thermic state ofthe engine.

From the above information and illustration, it is apparent that aself-compensating reducer has been constructed for compressed gases orl.p.g., in which the adjustment of the mass flow of the fuel during thedifferent working states of the engine does not depend on the pressureand temperature of the fuel in the bottle, nor on the thermic state ofthe engine. The idling speed of the engine, the consumption of fuel andthe emission of polluting gases can therefore be accurately controlled,whatever the working state of the engine. The resistors 37 provide thewalls of the body 1 in the proximity of the opening inlet 6 with amountsof heat which are sufficient for the instantaneous flow of the fuel,they keep the fuel at a constant temperature downstream from the openinginlet 6, and cooperate with the diaphragm to establish the correct massflow of the fuel to the engine.

I claim:
 1. A self-compensating and electrically heated reducer forcompressed gas or l.p.g. comprising: a supporting body; a chamber fittedwith an entrance connected to a bottle for compressed fuels or l.p.g.,and an outlet connected to an internal combustion engine; a diaphragmwhich at each variation of the internal pressure of said chamber, owingto the different amounts of feeding gas, controls a closing mechanismfor an opening inlet to keep said pressure inside said chamber constantbetween said entrance and said outlet in response to vacuum caused bysaid engine; said opening inlet being situated at the end of a firstchannel placed in said body between said entrance and said chamber, andsaid closing mechanism for said opening inlet controlling the flow rateof fuel, owing to the action of manoeuvring elements kinematicallyconnected to said diaphragm, and said closing mechanism controlling saidpressure of the fuel coming from said bottle; a thrusting mechanismwhich acts on at least one said manoeuvring elements to cancel theresultant or the momentum which results from the action of said pressureof the fuel on said manoeuvring elements, wherein said diaphragm isconnected to a first arm of a manoeuvring lever by means of a connectionrod which engages with a second arm of said manoeuvring lever, and saidclosing mechanism is situated at the end of a first plunger which actson the second arm of said manoeuvring lever by means of said thrustingaction brought about by said pressure of the fuel in said first channel,a second channel, which receives said thrusting mechanism, beingdisposed between said entrance and said chamber; said manoeuvring leverhaving a third arm opposite said first arm with reference to the pivoton which it pivots; said thrusting mechanism urging on the third arm tonegate the momentum of the first plunger's thrust with a thrust due tosaid pressure of the fuel in said second channel.
 2. A reducer as inclaim 1, wherein electrical resistors, connected with a feeding systemin said engine, are placed in thermic contact with the walls of saidbody.
 3. A reducer as in claim 2, wherein said electrical resistors areplaced near said opening inlet.
 4. A reducer as in claim 3, wherein saidresistors present a resistivity which varies in inverse proportion totemperature.
 5. A reducer as in claim 4, wherein said resistors are oftype P.T.C.
 6. A reducer as in claim 1, wherein the diameter of saidsecond channel is greater than the diameter of said first channel.
 7. Areducer as in claim 1, wherein said first channel is rectilinear, saidsecond channel having a rectilinear part parallel with said firstchannel.
 8. A reducer as in claim 7, wherein said thrusting mechanismcomprises a second plunger housed in said rectilinear part and a pusherfitted with a sliding housing in a cylindrical cavity; second plungerand pusher articulating said thrusting mechanism.
 9. A reducer as inclaim 1, wherein said manoeuvring lever presents an end which iskinematically connected to a connecting bushing integral with an end ofsaid connection rod.
 10. A reducer as in claim 9, wherein said end isintroduced in a spherically jointed housing situated in said connectingbushing.
 11. A reducer as in claim 10, wherein the coupling between saidhousing and said end is a free coupling permitting the rotation of saidend around the centre of said housing.
 12. A reducer as in claim 1,wherein said first plunger is integral with a push rod which rests onsaid first arm of said manoeuvring lever; said push rod reducing thedimensions of said first plunger to reduce its weight.
 13. A reducer asin claim 1, wherein sealing means are provided, which cooperate withsaid thrusting mechanism to prevent an unchecked flow of fuel towardssaid chamber through said second channel.